1) Field of the Invention
The present invention relates to an apparatus that removes a toner on an endless belt, such as a photosensitive belt or a transfer belt, which is used in the image forming apparatuses, such as electrophotographic printers, facsimile machines, and copier.
2) Description of the Related Art
In electrophotographic image forming apparatuses, an endless belt is used as a photosensitive belt, an indirect transfer belt, a direct transfer belt, to carry a toner. Particularly, due to layout restrictions, color electrophotographing apparatuses essentially requires the provision of a plurality of developing devices and a plurality of photoconductors, so that an endless belt, not a drum type belt, is often employed in such apparatuses. From the viewpoints of achieving size reduction and cost reduction, it is inevitable in design to minimize the number of rollers on which the belt is stretched and supported.
To clean toner from an endless belt, one approach is to provide a cleaning blade that abuts the endless belt. In this case, an opposing roller which supports abutment of the cleaning blade onto the belt is arranged inward of the endless belt so that a cleaning apparatus that is arranged at the roller that support the belt in such a way as to face the belt can be realized.
One of the rollers that support the belt should obviously be a tension roller to apply tension to the belt. It is desirable that the roller for abutting the blade onto the belt should be a fixed roller, not a movable tension roller, from the viewpoint of positional precision. However, from the layout restriction of individual units to be arranged around the belt and the restriction on the position of a drive roller which stabilizes driving of the belt, in addition to the aforementioned achievement of size reduction and cost reduction, it is sometimes advantageous for an image forming apparatus or a product as a whole to arrange the cleaning apparatus at the tension roller.
Japanese Patent Application Laid-Open No. H5-289426 discloses a technique for abutting the tension roller as an opposing roller onto the blade. However, the angle of abutment of the blade onto the belt may change due to a change in the position of the tension roller depending on the rotation fulcrum position of the cleaning apparatus or the layout restriction on the pressing direction of the tension roller. When there is a large change in the angle of abutment of the blade, inadequate cleaning may occur.